static void compute_twiddles(kiss_twiddle_cpx *twiddles, int nfft)
{
int i;
#ifdef FIXED_POINT
for (i=0;i<nfft;++i) {
opus_val32 phase = -i;
kf_cexp2(twiddles+i, DIV32(SHL32(phase,17),nfft));
}
#else
for (i=0;i<nfft;++i) {
const double pi=3.14159265358979323846264338327;
double phase = ( -2*pi /nfft ) * i;
kf_cexp(twiddles+i, phase );
}
#endif
}
/*
*
* User-callable function to allocate all necessary storage space for the fft.
*
* The return value is a contiguous block of memory, allocated with malloc. As such,
* It can be freed with free(), rather than a kiss_fft-specific function.
* */
kiss_fft_cfg kiss_fft_alloc(int nfft,int inverse_fft,void * mem,size_t * lenmem )
{
kiss_fft_cfg st=NULL;
size_t memneeded = sizeof(struct kiss_fft_state)
+ sizeof(kiss_fft_cpx)*(nfft-1); /* twiddle factors*/
if ( lenmem==NULL ) {
st = ( kiss_fft_cfg)KISS_FFT_MALLOC( memneeded );
}else{
if (mem != NULL && *lenmem >= memneeded)
st = (kiss_fft_cfg)mem;
*lenmem = memneeded;
}
if (st) {
int i;
st->nfft=nfft;
st->inverse = inverse_fft;
#ifdef MS_FIXED_POINT
for (i=0;i<nfft;++i) {
ms_word32_t phase = i;
if (!st->inverse)
phase = -phase;
kf_cexp2(st->twiddles+i, DIV32(SHL32(phase,17),nfft));
}
#else
for (i=0;i<nfft;++i) {
const double pi=3.14159265358979323846264338327;
double phase = ( -2*pi /nfft ) * i;
if (st->inverse)
phase *= -1;
kf_cexp(st->twiddles+i, phase );
}
#endif
kf_factor(nfft,st->factors);
}
return st;
}
